High density lipoproteins (HDL) may protect against atherosclerosis, since persons with high concentrations of HDL-cholesterol (and probably apolipoproteins A-I and A-II) have low coronary risk. While genetic factors appear to be important determinants of HDL levels, certain environmental and/or hormonal influences also affect HDL levels, increases occurring with exercise training, alcohol consumption (probable), estrogen (and possibly oral contraceptive) use, and clofibrate therapy and decreases with high carbohydrate feeding and anabolic, androgenic steroid treatment. However, whether these changes are mediated by parallel changes in apoprotein production and/or catabolism is unclear and perhaps more importantly, whether the changes in apo HDL levels and turnover are accompanied by the predicted changes in whole body cholesterol turnover remains unknown. Therefore we propose to develop and validate techniques of apo A-I and A-II turnover in whole HDL and HDL subfractions, establish published methods of whole body cholesterol turnover in our laboratory, and apply these techniques to the simultaneous measurement of apo-HDL and cholesterol turnover in dyslipidemic human subjects of specified lipoprotein and genetic classification before and during metabolic perturbation with exercise training, manipulation with high carbohydrate, fat-free or low-fat, moderate alcohol diets, or treatment with estrogens, oral contraceptives, oxandrolone (an anabolic steroid), or clofibrate.